1. Field of the Invention
The present invention relates to an automatic lifting and lowering controlling method that serves in installation of a heavy machine, such as a mobile power generating apparatus, or the like, on or removal thereof from a desired site, and an automatic lift/lower type platform controlling apparatus which is to be directly used for implementing the method.
2. Description of the Related Art
Conventionally, installation of a mobile power generating apparatus, or the like, on or removal thereof from a desired site has been performed by using a mobile large-sized crane, or the like, and the lashing crew therearound handling slings and other materials for load lashing.
However, loading and unloading of a mobile power generating apparatus, or the like, with a crane and by lashing work has presented a number of problems, such as that the operator of a crane is limited to the qualified personnel; that, if the crane used is large-sized, a wide working area is required to be secured, and that there is a hazard to the crew by a possible drop of load during operation of the crane, and the possibility of the load being damaged by dropping.
By the way, for the mobile power generating apparatus, it has been a general practice that the power generator is accommodated in a bonnet type (box type) container for reinforcement, and protection against outdoor weather, and minimization of the noise from the power generator; that the loading and unloading is performed by a crane to suspend the platform (also called chassis, bed, or base), on which the container is loaded, at the four side points thereof; and that, as the frame structural material on both sides of the platform, a channel steel material is used to provide a necessary strength.
In order to solve the above-mentioned problems, an automatic lifting/lowering platform apparatus A′, as shown in FIG. 10, which eliminates the need for lashing work, has been developed, allowing reduction of size of the mobile power generating apparatus; loading and unloading by a small number of crew members who are not limited to the qualified personnel, and thus reduction in the necessary numbers of working crew members; elimination of the hazard to the crew by a possible drop of load during operation of the crane, and the possibility of the load being damaged by dropping; and reduction of the working area required for transfer to or from the installation site.
Utilization of the automatic lifting/lowering platform apparatus A′ having the above-mentioned advantages has improved the safety and ease of the loading and unloading work, and reduced the cost.
Further, in the patent literature 1 as given below, the method for automatic lifting/lowering of a mobile power generating apparatus by utilizing the extending and contracting ability of the jacks in the automatic lifting/lowering platform apparatus A′, and the operator wirelessly operating a remote control operating apparatus for lifting/lowering the mobile power generating apparatus is disclosed.
Patent literature 1: Japanese Laid-Open Publication No. 2000-134729
However, the automatic lifting/lowering platform apparatus A′ as disclosed in the patent literature 1 has presented such problems as that, due to the difference in distance from the single pressure source to the respective jacks as automatic lifting and lowering means, the pressure loss and the pressure transfer rate vary, resulting in differences in operation timing and operation speed between jacks, and thus the vertical positions of the respective jacks vary, which can cause an inclination to be generated in automatic lifting or automatic lowering of the power generator, and thus a strain or a torsion to be produced, resulting in the joint waterproofing material on the outer plate panel being peeled off, which may lead to rainwater entering the interior and the door becoming impossible to be opened.
In addition, there has been a big problem that, if, as the frame structural material αa′ for the chassis α′ in the automatic lifting/lowering platform apparatus A′, the above-mentioned channel steel material is used, and for further reinforcement, an upper part structural material (a-H frame) and five-face outer plates and a bottom plate as shown in FIG. 8 (a), are provided, those materials may interfere with some component parts of the power generator, with the bottom plate having such a maintenability ill effect as that the oil pan cannot be removed, and in order to avoid these possible issues, the automatic lifting/lowering platform apparatus A′ has to be increased in size, which results in an increase in the weight as opposed to the lightweight which is required of the automatic lifting/lowering platform apparatus for mobile power generating apparatus.
The cause for the above-mentioned problems originate from that, as shown in FIG. 9 (a) and FIG. 9 (b), the form of stress has been changed from that for the four-point suspension by the crane (see FIG. 9 (a)) to that for the support by the four jacks in the outriggers β′ in the platform mechanism part of the automatic lifting/lowering platform apparatus A′ (see FIG. 9 (b)). Further, with the jacks in the automatic lifting/lowering platform apparatus A′, a phenomenon of two-point support on the diagonal line across the points X+ and X−, or Y+ and Y−, is occasionally caused. With the four-point suspension by the crane, the load imposed on one point by the suspension is approx. ¼ of the total weight, and the loading angle with respect to the vertical is equal for all the four. On the other hand, with the support by the four jacks, when the two-point support phenomenon is caused, the load supported by one jack is increased from ¼ to ½ of the total weight, i.e., doubled. In addition, the lifted sides of the structure hang down, and the direction of stress is alternately inverted. The member between Y+ and −X, and that between X+ and Y− are twisted to an extent which depends upon the load they bear. As a result of this torsion, a tension which has not been encountered in the suspension is applied to the top, bottom, and side outer plates. Such tension is transferred to the vibration absorbing rubber mounts and the outer plate panels, and the repetition of application of the tension has also caused the above-mentioned problems.
In addition, the hydraulic circuit open-close shock load occurring in the solenoid directional control valves for the jacks incorporated in the outriggers β′ in the automatic lifting/lowering platform apparatus A′ has further increased the above-mentioned torsion of the chassis α′, although this phenomenon was a transient one. Such hydraulic circuit open-close shock load was heavily generated when, in lowering, the contracting motion of the jack which caused the power generating apparatus to be greatly inclined was stopped.
Either the crane for loading and unloading or the automatic lifting/lowering platform apparatus A′ is driven on hydraulic power, but these differ from each other in the mechanism of occurrence and transfer of a shock caused by a hydraulic open-close valve. With the crane for loading and unloading, the shock is alleviated by the deflection of the long beams and the extension and contraction of the wires, but with the automatic lifting/lowering platform apparatus A′, there are no portions which can alleviate the shock, and thus the chassis is directly subjected to deflection and torsion, which can lead to occurrence of problems.
The inclination of the entire power generating apparatus can be easily verified at a location distant to some degree therefrom, however, the system with which the solenoid directional control valves are directly operated near the machine, the angle of the inclination cannot easily be recognized (the tardiness of angle recognition), which, in some cases, has led to an unnecessary inclination, and increased the shock load. The tardiness of angle recognition involved in the operation near the machine might cause overturning of the machine, resulting in the operator himself being injured by the overturned machine, thus with this system, the operator must have had to repeat a slight adjustment, and “a patrol around and inspection of the entire machine”.